[danjc]

I noticed a while back that Safari disallows HTML storage in private browsing more - dead giveaway. Chrome and FF allow it but probably clear storage when the session ends.

[ReverseCold]

Safari private browsing is to the point where if you open a new tab you're not signed into the same websites as your other tabs.

It's pretty annoying actually, but it's a good feature.

[saagarjha]

I think they may have relaxed that requirement a bit recently, so that you remain logged in if you click a link that opens in a new tab.